They’re harmonious on stage, but how well does Fifth Harmony’s Ally Brooke Hernandez know her bandmates in real life? The San Antonio native, 22, recently dropped by Us Weekly’s headquarters in New York to play a round of “How well do you know your squad?”

Us Weekly quizzed Hernandez on everything from which Fifth Harmony member is 5-foot-3 to who’s afraid of heights. The pop star also revealed which girl once peed herself — on stage at X Factor! “She was like, ‘Hey, producers, I have to go to the restroom, I can’t hold it in!'” Hernandez recalls. “They were like, ‘No, don’t worry, you can go afterwards.’ And when the doors opened . . . that’s when the show went on! She peed herself.”

Watch the video above to see how well Hernandez did with our game — plus find out which group member does a spot-on impression of Shakira!

After a European tour, the petite (4-foot-11!) songstress spent last fall raising awareness for March of Dimes. “I was actually a premature baby myself,” she tells Us. “My family knows what it’s like to go through the struggle of not knowing if your baby is going to be OK.” But don’t worry, Harmonizers: Hernandez still found time to join her group mates in the studio to work on the follow up to their debut album, Reflection, set for 2016. We know one thing for sure about the wait: It will be "Worth It"!